ABSTRACT
A bent intramedullary (IM) nail becomes challenging and technically demanding to the orthopaedic surgeon for nail extraction. A broken nail can be easily removed through the fracture site. However, a bent nail has to be broken before it can be removed. Several studies and case reports outline the strategies and techniques for removing a bent IM nail. However, there is a paucity of guidelines and standard protocol describing the best and inexpensive strategy. We report a case where two years following surgery for intramedullary nailing of the right femur, the IM mail was bent following secondary trauma. We used a technique based on the principles of an ability to fully cut the nail and extract it in two pieces by using a Jumbo cutter which is available in the orthopaedic armamentarium. This technique is simple yet economical, with the likelihood of causing less soft tissue damage and thermal necrosis.
ABSTRACT
Anisotropic X-ray Dark-field Tomography (AXDT) is a new imaging technique for reconstructing the three-dimensional scattering profile within a sample using the dark-field signal measured in an X-ray grating interferometry setup. As in any tomographic measurement, the acquisition geometry plays a key role in the accurate reconstruction of the scattering information. More- over, the anisotropic nature of the dark-field signal poses additional challenges for designing the acquisition protocols. In this work, we present an efficient approach to measure scattering orientations spread over the unit sphere and prove its efficacy using the knowledge from conventional tomography. In addition, we conclude (using analytical and experimental results) that placing the gratings such that the grating bars make an angle of 45 degrees with respect to the vertical direction is the optimal setup configuration for AXDT.
ABSTRACT
The x-ray dark-field signal measured in grating interferometers is anisotropic, depending on both the beam direction and the grating orientation with respect to the sample. We present a novel general closed-form, continuous forward model of the anisotropic dark-field signal. Furthermore, we derive a discretization using spherical harmonics, leading to a large-scale linear inverse problem. We present first experimental results of a wooden sample, demonstrating marked advantages over previous results, in particular, the resolution of multiple scattering directions in one volume element.
ABSTRACT
An analysis is made of an infrared chopper based on the refraction of light rays by a low frequency (~l-MHz) standing acoustic wave in a block of material such as germanium. Computer programs are described for tracing the rays through the acoustic field and for calculating the contrast ratio at a small aperture detector following the chopper. Experimental results obtained with a germanium device are in good agreement with the theory.
